2.0 Analysis 2.1 Introduction The analysis will focus on maintenance management, the engine failure, the aircraft altitude and position at the time of engine failure, the pilot's reactions, fatigue, the aircraft rudder trim, the loss of control, and pilot training. 2.2 Maintenance Management Some of the deficiencies identified during the 1992 TC audit were apparent during the occurrence investigation. Aircraft defects were not being consistently recorded in the aircraft log-books; nor were there records to show the status of recurring defects between inspections. Compliance with ADs and component SBs was not being entered in the aircraft log-books as required under ANO VII, No. 2 and No. 3, and the Airworthiness Manual, 575. Had the magneto impulse coupling inspection been completed as required by AD 78-09-07 R3, the wear patterns could have been detected and rectified before the magneto failed. Although TC audits had identified such shortcomings and the company had reported corrective action, many of the shortcomings were still present at the time of the accident. 2.3 The Engine Failure The magneto impulse coupling flyweights were worn beyond the prescribed limits. When the flyweight jammed against the stop pin, the secondary gear train failed and the engine stopped abruptly. 2.4 Altitude and Position on Departure The altitude and position of the aircraft when the pilot encountered the engine problem could not be determined with certainty. The pilot did not report his altitude during the transmissions with the FSS. On the inbound trip from Inuvik, the pilot remained below the cloud base and, if he followed his past flying habits, he likely would have remained below the 1,100-foot cloud layer for the return trip. The thin layer of rime ice on the tail of the aircraft could have accumulated either inbound to Tuktoyaktuk, or on the departure. The possibility also exists that the pilot could have inadvertently entered cloud while handling the emergency. 2.5 Pilot Reactions Two scenarios were studied to help understand why the pilot was unsuccessful in flying the aircraft back to the airport on one engine. There was no way to determine which of the two scenarios is more likely; however, it is clear from the evidence that the aircraft was not in controlled flight when it hit the ice. The first scenario examines the possibility that the pilot climbed into or above the cloud layer. If this were the case, the lower cloud bases at Inuvik would likely have necessitated an IFR approach to the Inuvik Airport, after which the pilot could have continued VFR to the townstrip. While the pilot held an IFR rating, the aircraft was not equipped with an autopilot and, since there was only one pilot on board, IFR would have contravened ANO VII, No. 3. The second scenario examines the possibility that the pilot remained VFR below the clouds. The lights from the Tuktoyaktuk Airport and hamlet would have been behind him. In this case, he would have had few visual references and little or no horizon to provide attitude reference. If he was successful in turning the aircraft toward the airport, with the reported 15 miles visibility, the lights should have become visible. If he turned the aircraft using the ground lights as a visual reference, and if he was, at the same time, preoccupied with carrying out the engine failure emergency procedures, he could have become disoriented and lost control of the aircraft. However, it could not be determined how much of the turn back to the airport was accomplished. Given the existing conditions and the fact that the pilot was instrument rated, it is concluded that he would have referred to the aircraft flight instruments while handling the emergency, and probably the GPS and/or the Tuktoyaktuk NDB for directional information. 2.5.1 Fatigue The pilot reportedly had good sleep habits, and had adequate rest the previous night. His duty day and flight times on the day of the accident were within established limits. However, according to the aircraft log-books, his most recent non-flying day was 11 November, 22 days prior to the accident. During the last four-month period there were 13 days when he did not fly. ANO VII No. 3 specifies one rest period of at least 24 hours in each seven-day period, or 13 times each calendar quarter. Typically, small air carriers do not have a clearly delineated policy that distinguishes between rest days and non-flying days. Frequently, pilots may not be scheduled to fly on a certain day, but are available if needed for flying and/or related duties. It could not be determined if the pilot's work schedule during the last four months led to some degree of fatigue which could have affected his judgement and reactions to the emergency. 2.6 Aircraft 2.6.1 Stall Warning and Instrument Lighting It could not be determined to what extent, if any, the apparent unserviceability of the stall warning and the cockpit lighting affected the pilot's performance. However, if he needed to refer to the rudder trim indicator on the overhead panel, it would have been difficult to read the indication if he was not using his flashlight. 2.6.2 Single-Engine Procedures/Performance The throttle and propeller controls were found in a position that would indicate that the pilot properly identified the failed engine and followed the emergency engine shutdown procedure. According to the manufacturer's calculations, at a gross weight of approximately 6,200 pounds (400 pounds below the maximum gross weight), and a C of G of approximately 23.9 inches aft of datum, the aircraft would have been capable of returning to the airport on one engine.